The present invention relates to a cap unit for a fuel tank of a vehicle.
Vehicles, such as a motorcycle, incorporate a fuel tank for storing fuel which is supplied to an engine thereof, the fuel tank having a fuel supply port, at its upper end portion when mounted, which is closed by a cap unit.
A cap unit 5 has a structure formed as shown in FIG. 5 and incorporate a cap body 2 for closing a fuel supply port 1 which is brought to a locked state by engaging a front claw 3a of one lock bar 3 to an engaging portion 4 provided for the fuel supply port 1.
The cap body 5 is brought to an unlocked state by disengaging the front law 3a of one lock bar 3 from the engaging portion 4.
The cap unit 5 further incorporates a mount base 6 having the cap body 2 extending therefrom. The mount base 6 is secured to a mount base securing portion a fuel tank 7 by one of more bolts (not shown) and is pivotable around a hinge pin. Thus, in the unlocked state, pivotally rotating the mount base 6 rotates the cap body and thereby opens or closes of the fuel supply port 1. However, if the one or more bolts are loosened because of inadequate maintenance or intentional removal, the overall body of the cap unit 5, even in the locked state, may be removed by, for example, scooping out the cap unit 5. If the cap unit 5 in its locked state can be removed from the fuel supply port 1, fuel may be stolen easily. Furthermore, there is a possibility that fuel may rapidly leak out of the fuel tank 7 unknowingly. There has been provided (refer to Japanese Patent Laid-Open Publication No. HEI 9-24874) which incorporates an engaging projection 8 provided for the outer wall, side portion, of the cap body 2 on the rear of the lock bar 3. When the overall body of the cap unit 5 is moved upward in the lock state in which the front claw 3a of the lock bar 3 is engaged to the engaging portion 4, the engaging projection 8 is engaged to the engaging portion 4.
The contact of the engaging projection 8 to the engaging portion 4 must be prevented during a usual operation for opening or closing the cap body 2. Therefore, as shown in FIG. 5, somewhat long distance x is required between a locus 9 of the engaging projection 8 when the cap body 2 is opened or closed and the lower end of the engaging portion 4. However, if the distance x is too long, the original function, that is, prevention of the removal of the overall body of the cap unit 5 owning to the scoop-out of the cap unit 5 cannot be realized. Therefore, each of distances y and z between the engaging projection 8 and the engaging portion 4 must have great dimension accuracy.
If the distance y between the upper surface of the engaging projection 8 and the lower end of the engaging portion 4 is too large in order to prevent contact of the engaging projection 8 to the engaging portion 4 when the cap body 2 is opened or closed, looseness sometimes takes place in a state in which the bolt for securing the mount base 6 to the fuel tank 7 is loosened or in a state of no bolt. Therefore, the hermeticity of the fuel, tank 7 is sometimes deteriorated. If the distances y and z between the engaging projection 8 and the engaging portion 4 are too short, there is apprehension that the engaging projection 8 is brought into contact to the fuel supply port 1 when the cap body 2 is opened or closed.